• By magnifying prior to the viewer with the Baader Glasspath Corrector - 1:1.7, the effects of any optical tolerances and misalignments in the centering of the eyepieces are reduced.
• A compensator enables the use of longer focal length eyepieces to achieve high magnifications, which tend to have longer eye relief (greater comfort) than short focal length eyepieces. 

Please note, there are Three Glass path correctors of different focal length's available to supply perfect color correction and to suit all focussing needs.

-Glasspath corrector, Factor 1.25 (#2456314) – moves focus out to a minimum 15mm (may vary slightly from scope to scope)
-Glasspath corrector, Factor 1.70 (#2456316) – moves focus out to a minimum 35mm (may vary slightly from scope to scope)
-Glasspath corrector, Factor 2.60 (#2456317) – moves focus out to a minimum 85mm specially designed for Newtonian telescopes.

Some people choose to have more than one compensator to allow for a different range of magnifications, firstly you should work out how much back focus your scope allows (with various adapters and diagonals in place), then choose a suitable compensator to push the focus out to encompass that distance (+/- 5mm would be advisable just to be confident as there is some small tolerances)